HOLLEY 500 CFM ULTRA XP 2BBL CARBURETOR - HLY-4412BK

The original Holley 0-4412 has powered thousands of racers to the winners' circle! How do you make it better? Add the proven design elements of the popular Ultra series for more tunability, more durability, more weight savings and more features! The Ultra XP 2bbl carburetors feature all aluminum construction for nearly 50% weight savings over their zinc counterparts, contoured venturi inlet for unobstructed airflow, screw in air bleeds for easy fine tuning, black anodized fully adjustable billet aluminum metering block and baseplate, high capacity fuel bowl which features 20% more fuel capacity to eliminate starvation, integrated fuel shelf to minimize fuel aeration and internal baffling to control fuel slosh and a centered air cleaner flange for improved airflow and performance. Other notable features include wedged floats, knurled hand adjustable curb idle screw and down leg boosters. Ultra XP 2bbl carburetors are approved for use in NASCAR® Mid-West/West Coast Late Model Divisions and utilize the same venturi and throttle bore dimensions of the classic 4412 2bbl carburetor. Available in shiny (Day HLY-4412BK / Holley 0-4412BKX) or Hard Core Gray (Day HLY-4412HB / Holley 0-4412HBX) finishes, the Ultra XP 2bbl will outperform any production 2bbl available.

Features:

• All aluminum construction - for nearly 50% weight savings over zinc version
• Tumble polished aluminum with Black™ billet aluminum metering block and base plate
• No choke tower for unobstructed airflow
• Air bleeds moved outward to allow a smoother transition of airflow
• Air cleaner flange centered over venturii for improved airflow and performance. 5/16-18 bent air cleaner stud included
• Down-leg boosters for improved fuel signal
• Contoured hex head squirter screw for streamlined airflow
• Internal pump passage on metering block equipped with tunable bleed off
• Same 1-3/8” Venturii & 1-11/16” Throttle Bore size and Throttle Plate/Throttle Shaft size of original 0-4412
• Fuel bowl provides 20% more fuel capacity while controlling slosh with internal baffling
• Clear sight windows on both sides of bowl for easy & safe fuel level adjustments
• Fuel trough designed into floor of bowl to route fuel flow directly to the jets and assists in keeping jets covered by fuel
• Built in drain plug provides easy access to empty contents of bowl
• -8 (O-ring) inlet threads offer a large variety of plumbing options (come with an extended -8 O-ring to -8AN male adapter and -8 plug). Can be plumbed from either side
• Throttle shaft rides in oil impregnated sintered bronze bushings for smooth throttle actuation
• Throttle shaft capped to prevent entryo f debris & contaminates
• 30cc pump with metal lever. Anti-siphon valve in mainbody to reduce pump pull over
• Dedicated race-only throttle lever with all unnecessary street attachment points & tangs removed
• Knurled (hand adjustable) curb idle screw allows for easy idle adjustment without the use of tools
• Set screw for wide open throttle stop adjustment
• Wedge float provides fuel control while cornering
• 100% wet-flow tested by Holley technicians to assure it arrives ready to run!

Resources

• 0-4412HBX and 0-4412BKX Installation and Adjustment Instructions.pdf